Uh, he's 40, not 60+
Little's age needs to be at least 50-55 the way they portray him.
I'm not saying he could match all the 20 something year olds in running (distance and speed), and boxing (duration and reflexes and strength), and especially combat reflexes, but having him run about 30 seconds and be out of breath? Having him get knocked to the mat in boxing and then not be able to stand up straight or walk faster than someone 2 days out of major surgery the next day? Come on.
These are things that, first, could happen to any out of shape person of any age and, second, don't easily happen to in shape people of about any age (and especially age 40!).
Also, the "bad guy" pilot looks at least 50, so why is he so good with reflexes? It's not just his helicopter that makes him so hard to kill! So there's a blatant inconsistency.
I'm 39 (and Little just turned 40 so we are almost exactly the same age) and I have noticed little to no difference in my physical limitations in terms of endurance or recuperating ability since I was in my teens or 20's or early 30's. I know that's partly due to the slow and gradual affect of aging and not being able to directly compare myself at age 18 or 25 or 30 to age 39 (such as being able to do a number of endurance exercises at my present age and then immediately jump back in time to age 18 or 25 or 30 to do the same activity in order to compare my endurance, speed, and any soreness--and duration of the soreness), but it's not just a matter of these cognitive limits affecting my knowledge of my present abilities compared to my past abilities. No, it's due to there not really being a large difference.
In fact, in matters I can directly compare via quantification, such as long distance cycling (I've used a cycling computer ever since I started cycling seriously) which I have done since I was a teen, I do the same amount of miles in a week as I've always done (70+) at the same average speed (21 mph). I also go on 5-10 mile hikes on difficult terrain in the same time duration as I've done since I was a teen, go on 2 or 3 day long backpacking trips covering 50+ miles as I've done since my early 20's, play tennis for the same amount of time, weight lift the same weight, and same reps, since I started in my teens and leveled off in my early 20's (didn't want to gain any more mass or strength)...etc. I haven't noticed any limitations in my abilities in these areas and I even keep up just fine with those up to 20 years younger than I in cycling and hiking (I often go in groups) and I frequently beat people of my skill level in tennis who are in their teens or early 20's and so should have better reflexes/speed than I.
And I'm not boasting or deluded; in fact, I know people 10-20 years older than I who can and do 1) cycle more miles per week than I do at the same or close average speed, 2) beat me at tennis, 3) keep up with me on any hike, 4) weight lift higher volumes than I with more reps. I even know people in their 70's and 80's who cycle 25 miles at a time (though they can't match the speed of those decades younger) and go on long difficult hikes (though they will take longer to do them). They may not cycle or hike as much per week as they did in their pre-60 years, but they are hardly all feeble old people who can barely walk to their mailbox without stopping or taking 5 minutes to do it at a shuffling pace either. They actually can out perform an average in shape (not totally out of shape, but not really in shape either) person decades younger than them. I even often witness them doing it.
Basically, the human body only starts to really age after age 50 and even then it's a slow decline and people into their 70's and 80's can still do a regular impressive amount of exercise. This movie was nuts to act like a 40 year old, who is in his prime (prime is late teens to 50-55) is some feeble old man who can't run for 30 seconds without gasping for breath or fall on a boxing mat without being severely sore the next day. It'd be one thing if they were making a point of him being out of shape, for yes these things will happen to any out of shape person of any age, but they weren't: his age was emphasized over and over, not his status of physical shape.
PS: I still often get carded when I order alcohol at a restaurant or buy it at a store, even though I always get what a young person would usually not (i.e. I order or buy expensive craft beers and wine: not cheap/generic big brand swill like a 19 year old).